In a previous roundup we wrote that if you were planning on traveling for the holidays, your friends on Facebook likely knew where you were headed. Thanks to Facebook’s Open Graph, users are now going beyond simple “likes” with “hire,” “book,” “stay,” and other relevant actions for planning travel. As Tnooz’s Kevin May points out, almost all trip planning sites have integrated the sharing elements of social media. But travel sites – especially those that have just launched – might soon face competitive pressure from Facebook, the very site that...